This invention relates to orthopedic appliances and more specifically relates to removable appliances for substantially immobilizing the ankle joint. One of the most common orthopedic injuries is the ankle sprain. This injury occurs when there is sudden forceful hyperinversion or hypereversion of the ankle joint. The ligaments connecting the ankle bones (malleoli) to the foot are thus partially or completely torn. There is immediate pain and inability to bear weight on the affected limb. Swelling then occurs at the site of the injury, generally in proportion to its severity.
Treatment objectives are to relieve pain and to promote healing of the torn fibers of the involved ligaments. These objectives are accomplished by immobilization of the affected joint in a neutral position and reduction of the distortion of the joint due to swelling. Elevation, compression and cold applications, initially, followed by alternating cold and warm baths later in the course of treatment, are valuable adjuncts.
Immobilization is accomplished by a variety of methods. One method is to wrap an elastic bandage around the foot and ankle, occasionally incorporating U-shaped felt pads that are placed so that the soft tissue surrounding the malleolus is compressed to minimize swelling. Crutches are used for partial weight bearing for several days or weeks. The elastic bandage does not afford the complete immobilization needed for solid healing of severely torn ligaments and its use is associated with a higher incidence of reinjury. Daily activities are limited by the associated use of crutches.
A second method of immobilization is the application of a plaster cast with the addition of a walking heel or boot. Plaster casts permit firm immobilization, but require a two- or three-day period of walking with crutches, using extreme care not to bear weight on the cast because to do so causes it to soften, rendering it useless. Since these casts usually stay on for at least two weeks before they are removed and/or replaced, they cause itching and sometimes dermatitis secondary to perspiration and bacterial overgrowth. As tissue swelling about the ankle decreases and muscle atrophy occurs in the calf, the cast becomes loose and uncomfortable. Thus, the extremity should be recasted, entailing more physician time and expense and another period of crutch usage.
Another method of treatment involves the application to the ankle of various preformed apparatus, such as braces and nonplaster casts. In spite of some apparent advantages, none of these appliances has ever gained popular acceptance. It is suspected that one reason for the lack of acceptance is the failure of the appliance to account for the bilaterality of the extremities, i.e., left and right sides. When one observes the foot and ankle it is is apparent that there are marked differences between the medial and lateral aspects. First of all, the medial side is larger. Secondly, the first metatarsophalangeal joint is located anteriorly to the fifth metatarsophalangeal joint and is more prominent. Thirdly, there is an arch located on the medial aspect of the foot but none on the lateral aspect. Fourthly, the medial malleolus is located anteriorly and superiorly to the lateral malleolus. The foregoing anatomical facts would seem to preclude a comfortable fit by any snug fitting cast or apparatus that encases the foot and ankle but does not incorporate at least some features of bilaterality into its design.
In addition, it is noted that the prior art appliances typically apply pressure evenly over the entire ankle without consideration that there should be less pressure over the bony prominences (malleoli) and greater pressure over the surrounding soft tissue in order to reduce swelling around the torn ligaments.
It is therefore an object of the present invention to provide a splint for immobilizing the ankle joint that is capable of being worn comfortably for two to eight weeks, depending on the severity of the sprain, to ensure complete ligamentous healing.
It is a further object of this invention to provide such a splint that allows early ambulation without the use of crutches so that little time is lost from work, school, or other activities and that incorporates a walking surface as an integral part of the unit.
It is another object of the invention to provide a splint that is easily applied, easily removed for bathing, rest and physical therapy and is easily reapplied.
It is also an object of the invention to provide a splint that is adjustable to accommodate tissue swelling and muscle atrophy as well as individual variations in anatomy and that, once adjusted, stays firmly in place.
Still another object of the invention is to provide a splint that can be produced for both left and right lower extremities and takes into account the anatomical differences between the medial and lateral aspects of the ankle joint as well as preventing pressure directly on the malleoli while applying increased pressure over the peri-malleolar tissue to decrease edema and thereby promote healing of torn ligaments.